According to researchers in Spain, a maternal vitamin D deficiency during pregnancy could adversely impact the mental and motor skill aspects of brain development in babies.

Led by Eva Morales, PhD, a medical epidemiologist in the Centre for Research in Environmental Epidemiology (CREAL) in Barcelona, researchers measured the level of vitamin D in the blood of nearly 2,000 women in their first or second trimester of pregnancy and evaluated the mental and motor abilities of their babies at about 14 months of age.

At 14 months of age, neurocognitive and psychomotor testing revealed that mothers with levels above 40 ng/ml had infants with the best brains. The improvement curve appeared to improve slightly with a maternal level of 50 ng/ml, but the difference did not appear to be significant.

The researchers found that children of vitamin D-deficient mothers scored lower than those whose mothers had adequate levels of the sunshine vitamin. “Lower scores in these tests could lead to lower IQs among children,” said Dr. Morales. “These differences in the mental and psychomotor development scores do not likely make any difference at the individual level, but might have an important impact at the population level.”

In fact, according to this study, as part of INMA project, the difference between four and five points in this type of neuropsychological test could reduce the number of children with intelligence above average (IQ of 110 points) more than 50%, Dr. Morales said.

The researchers acknowledged that other factors might have influenced the babies' mental and motor development, including birth weight, maternal age, social class and mother's education level, and whether or not the mother drank alcohol or smoked during pregnancy.

The study, published in the journal Pediatrics, concluded that 20% of women had deficient levels of vitamin D and another 32% had insufficient levels of the vitamin. However, Dr. Morales added that “you do not need to take vitamin supplements, only follow a balanced diet and be as healthy as possible and enjoy the sunshine.”

Ruth Lawrence, PhD, medical director of the Breastfeeding and Human Lactation Study Center at the University of Rochester Medical Center in New York, explained to HealthDay that this study did not address the diet of the babies. Although vitamin D is in both breast milk and infant formula, cholesterol and the amino acid taurine are only found in breast milk and also affect brain development after birth, she said. In addition, Dr. Lawrence advised that pregnant women should get a dietary consultation in their first trimester and consider vitamin D supplementation. “We have realized that vitamin D has a lot more impact than to prevent rickets,” she said.

Vitamin D has amassed a growing volume of research regarding its benefits. Previous studies have also linked insufficient levels of vitamin D during pregnancy with language impairment in children at 5 and 10 years of age.

Despite all of the published studies, experts continue to debate how much vitamin D pregnant women should consume. The Institute of Medicine recommends pregnant women get 600 IU/day of vitamin D and no more than 4,000 IU/day, whereas the Endocrine Society advises a dose of at least 1,500 to 2,000 IU/day.

In an interview with HealthDay, Bruce Hollis, PhD, director of pediatric nutritional sciences at the Medical University of South Carolina in Charleston, explained that the recommended 600 units per day was likely sufficient enough to promote good skeletal health in fetuses, but did virtually nothing to prevent other diseases.

But that’s not to say vitamin D isn’t beneficial for pregnant moms. Research led by Dr. Hollis found that pregnant women taking vitamin D could lower their risk of pregnancy-related diabetes and high blood pressure. He also pointed to studies that determined that low levels of prenatal vitamin D levels could weaken a baby's immune system and increase the risk of asthma and other respiratory conditions, and heart disease. To that end, Dr. Hollis recommended that women who are pregnant or want to become pregnant consume 4,000 units a day of vitamin D. He also said 10 to 15 minutes per day in the sun during the summer is also a good way to get vitamin D.

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